testsuite: plain chars are never compatible with [un]signed chars

In standard C, plain chars are either signed or unsigned but are only
compatible with themselves, not with signed chars nor with unsigned ones.

However, Sparse has this wrong and make them compatible with the
corresponding sign-qualified chars.

So, add a testcase for this.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/validation/plain-char-compatibility.c b/validation/plain-char-compatibility.c
new file mode 100644
index 00000000..cdfe1a31
--- /dev/null
+++ b/validation/plain-char-compatibility.c
@@ -0,0 +1,19 @@
+static int sfoo(void)
+{
+	return __builtin_types_compatible_p(char, signed char);
+}
+
+static int ufoo(void)
+{
+	return __builtin_types_compatible_p(char, unsigned char);
+}
+
+/*
+ * check-name: plain-char-compatibility
+ * check-command: test-linearize $file
+ * check-known-to-fail
+ *
+ * check-output-ignore
+ * check-output-pattern(2): ret.*\\$0
+ * check-output-excludes: ret.*\\$1
+ */